Science Note: Turning up the volume on the mating dance

Air Date: Week of August 24, 2012
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A male peacock struts with his eye-spotted plumage held high. (Photo: Jebulon/ Wikipedia)

The peacock is notorious for its unique mating display, where it raises up its ornate eye-spotted tail and shakes. Now, new research tells us humans can't quite experience the full show. Christy Perera reports.

Transcript

CURWOOD: The peacock is known for its beautiful plumage and elegant mating dance. New research shows there's more to the dance than meets the human ear.

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PERERA: During the mating season, male peacocks grow a long, elaborate train of feathers. They raise this massive collection of plumage upright and shimmy to attract a mate. To the human ear, this sounds similar to rustling leaves. But researchers at the University of Manitoba found that peacocks actually produce other low-pitched sounds during the dance. These noises, called thrums, fall below 20 Hertz and can't be detected by humans.

Male peacocks create two kinds of thrums--the 'pulse train' and the 'shiver train.'
The 'pulse train' starts at the base of the train feathers and summons females close by. Peacocks create the 'shiver train' by shaking their center feathers and use this to signal potential mates further away.

These brightly feathered birds are the first avian species known to create and respond to sounds below the range of human hearing. Only one other species, a member of the grouse family, has been recorded creating infrasounds like these thrums. But those grouse didn't react to recordings of infrasound, so it's unlikely they use the sounds for communication.

Biologists suspect that if peacocks can rumble, other birds can too. And thanks to this research, it's clear the mating dance is music to a bird's ears.

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